Sprint Heat Time Trends

Since I’m starting to accumulate a reasonable collection of heat times from World Cup sprint races, I thought it might be interesting to compare general trends between the few seasons I have data on.

The biggest trends that you can typically see are the differences in tactics between the men and women. Generally what I’ve seen is that the women will ski qualification fairly conservatively and then the heat times will get progressively faster with each round, although possibly tailing off slightly in the finals. The men are generally more “tactical” in that they tend to really hammer qualification and then get a bit more cagey during the heats.

I was curious if these characteristics had changed much over the short time period I have data:

The units on the y axis aren’t in seconds, since I have to standardize the time differences to compare values from different races. But larger values are slower, smaller values are faster, and everything is relative to the median heat time for the entire day, which is pegged at zero.

You can see that the general impressions that I outlined above were strongly influenced by what I saw in the data during the 2010-2011 season, which was where these trends were most stark. This most recent season was mostly similar for the men, although somewhat more variable (shaded region indicates, roughly, variability). Interestingly, though, the women’s data changed pretty dramatically this past season. The qualification round times were in general quite a bit faster relative to later rounds than they have been in the past, and the later rounds became slightly slower, or more “tactical” perhaps.

Comments

Question: Does this data really show skiers getting faster throughout the day? Or does it show the average heat times getting faster because only the fast people are left? I.e., the fast people just keep skiing fast like they did in the qualification round, but because the slow people from the qualis and quarters are gone, the median times are faster?
Just wondering. My impression has always been that nobody held much back in the qualifiers, men or women, though perhaps that happens a bit more in the quarters and semis. The Canadian men always talk about how easy people are skiing in the early rounds.
I’d also be interested in seeing the average length (in time) of races over the years–i.e., we know sprints are longer now than they were eight years ago…were they longer last season than they were two or three seasons ago?

If I literally said that the skiers were getting faster, that was simply sloppy writing on my part. A lot can change between qualification and the finals, even the snow conditions. So the best we can do is the relative comparison: compared to the median head time for that day, the times in the finals tend to be faster/slower, etc.

If you were right, and the dominant effect was the weeding out of slower skiers, we’d expect that the “average” heat time would always get progressively faster throughout the day, but that certainly isn’t the case. In particular, the large difference in trends between the men and women suggests to me that there really is something else going on that’s influencing this.

For example, when you get to the semis, I’ve definitely seen plenty of cases with the men where the times for the two heats are really radically different, but I feel like that’s much less likely with the women. That’s just my general sense, though, from making those graphs every week all winter.